Replacing gold with nickel in quantum dot solar cells could reduce costs by 40% – 80%. Researchers at the University of Toronto have shown that it is possible to do this. From the news item on Azonano,

At first, nickel did not appear to do the job. “It was intermixing with our quantum dots, forming a compound that blocked the current flow from the device,” says Dr. Ratan Debnath, first author on the group’s paper [in the July 12, 2010 issue of Applied Physics Letters]. Adding just one nanometer of lithium fluoride between the nickel and the dots created a barrier that stopped the contamination, and the cell’s efficiency jumped back up to the expected level.

This is the latest of several recent solar-cell milestones by the Canadian researchers. “We have been able to increase dramatically the efficiency of our photovoltaics over the last several years and continue to hold the performance world records,” Professor [Ted] Sargent said.

In addition to making solar cells cheaper to produce, the group is working on increasing the cells’ power-conversion efficiency to 10% before attempting commercialization.